Where to Set Feed Rates?

[Ken Alexander`]

Hi All,

I'm a new CNC router owner and a new Cut2D Desktop (and DrufelCNC) user. On my first "cut" (1mm deep in some hardwood with a 1.5mm endmill) the router did a neat job but it was very noisy, noisy enough that I stopped it partway through the job. It looked and sounded like it was trying to cut faster than it should.

When creating toolpaths Cut2D allows you to specify the material to be worked on, which I assume determines the "feeds and speeds" though it doesn't explicitly say so (that I can find). Meanwhile, DrufelCNC's generic settings video recommended setting the speed of the X, Y and Z axes each to 1,500 mm/min with no regard to the material to be cut. I don't have enough experience with this to know if the two settings I'm seeing are indeed related or not. So, a few questions:

1. Does selecting a material in the Cut2D toolpath setup determine the feed and speed for that job? If so, how can I determine what numerical settings they correspond to? I understand that there are other forces at work here, like depth of cut, etc., which just makes it harder to know what the right numbers are.

2. Are feeds and speeds part of the G-code that Cut2D generates?

3. Is the 1,500 mm/min setting in DrufelCNC overriding any feed and speed information (if there is any) coming from the Cut2D G-code?

That should do it for now. Many thanks in advance. Brace yourself for many more questions!

Ken

[Adrian]

1. The feed rates are part of the tool you select from the database when you create the toolpath. You can change them in the tool database (you must then re-select the tool) or use the Edit button in the toolpath itself to change them just for that toolpath.

2. Yes the feed rates are output as part of the code using the rates defined for the tool as above.

3. Don't know on that one.

One thing to bear in mind is that there are two primary types of moves with CNC machines. Feed rate moves and rapid moves. The feed rate is set in the tool database but the rapid rate moves (when the tool is in the air and moving to the next cut) is specified in the control software itself. That might be what DrufelCNC are talking about.

[Leo]

Correct feeds and speeds MUST be determined by the operator.

Yes there are some settings in Vectric but they are not specifically designated for your machine or material. They are just some numbers to fill the spaces. I don't know how those numbers are derived.

Thinks to learn about and consider when determining speeds and feeds

1) Chipload. How much material is being removed per 1 revolution of the cutter. Most cutter manufacturers have a recommended chipload on their website. Proper chipload can be varied based on manufacturer range.

2) RPM. Going too fast with too low a feedrate will heat the cutter and burn it.

3) Feedrate. This works in conjunction with RPM to achieve the correct chipload

4) tool length. The amount the tool is sticking out of the collet. The more the stickout the more the cutter is likely to chatter, or scream. NEVER clamp on the flutes

5) Machine rigidity. RPM and FEED can be adjusted to maintain chipload, and feed can be slowed to account for a less than rigid machine. Keep in mind that slowing feed also needs to adjust RPM to maintain chipload.

6) Do an internet search for a chipload calculator to calculate chipload FREE

7) Adjust your speed and feed to best suit YOUR machine. There is NO cookbook approach to this.

[Ken Alexander`]

Thanks Adrian,

This is making a lot more sense now. I see the settings in the tool database. Since Cut2D doesn't know what router I'm using then I can see I have a lot more setting up to do!

What you suggest about the rapid rate in DrufelCNC makes sense.

Many thanks for your help!

Ken

1. The feed rates are part of the tool you select from the database when you create the toolpath. You can change them in the tool database (you must then re-select the tool) or use the Edit button in the toolpath itself to change them just for that toolpath.

2. Yes the feed rates are output as part of the code using the rates defined for the tool as above.

3. Don't know on that one.

One thing to bear in mind is that there are two primary types of moves with CNC machines. Feed rate moves and rapid moves. The feed rate is set in the tool database but the rapid rate moves (when the tool is in the air and moving to the next cut) is specified in the control software itself. That might be what DrufelCNC are talking about.

[Ken Alexander`]

Hi Leo,

I replied to your very helpful post yesterday but I don't see it today so I'll try again.

As luck would have it Cut2D has a chip load calculator in the tool setup section, which was very helpful as I learned about chip load today. I have a basic grasp now and will keep reading up on it as I enter the rest of my tools into the database.

Many thanks again for your help. You've given me a lot to work on and I appreciate it!

Ken

Correct feeds and speeds MUST be determined by the operator.

Yes there are some settings in Vectric but they are not specifically designated for your machine or material. They are just some numbers to fill the spaces. I don't know how those numbers are derived.

Thinks to learn about and consider when determining speeds and feeds

1) Chipload. How much material is being removed per 1 revolution of the cutter. Most cutter manufacturers have a recommended chipload on their website. Proper chipload can be varied based on manufacturer range.

2) RPM. Going too fast with too low a feedrate will heat the cutter and burn it.

3) Feedrate. This works in conjunction with RPM to achieve the correct chipload

4) tool length. The amount the tool is sticking out of the collet. The more the stickout the more the cutter is likely to chatter, or scream. NEVER clamp on the flutes

5) Machine rigidity. RPM and FEED can be adjusted to maintain chipload, and feed can be slowed to account for a less than rigid machine. Keep in mind that slowing feed also needs to adjust RPM to maintain chipload.

6) Do an internet search for a chipload calculator to calculate chipload FREE

7) Adjust your speed and feed to best suit YOUR machine. There is NO cookbook approach to this.

[Leo]

Thanks for the reply Ken.

Chipload is the key ingredient.

Find out from the cutter manufacturer what is a reasonable chipload for your cutter. If you cannot find it on your cutter manufacturer other manufacturers are going to be about the same.

You should use a 1 or 2 flute cutter - don't use 4 flutes.

Chipload on a 1.5mm should be ABOUT >> .002" - .004" MAYBE as low as .001" but try not to go that low.